Engine room telegraph



Feb. 2, 1954 H. H. CURRY 2,668,285

ENGINE ROOM TELEGRAPH Original Filed March 14, 1946 3 Sheets-Sheet 1' STARBOAPD WING CONTROL PORT WING CONTROL WHEELHOUSE. CO NTROL.

FIGLI.

| HERMAN- H.CURRY INVENTOR ENGINE ROOM CONTROL 1954 H. H. CURRY 2,668,285

ENGINE ROOM TELEGRAPH Original Filed March 14, 1946 3 Sheets-Sheet 2 HERMAN HLURRY INVENTOR ATTORNEY Feb. 2, 1954 H. H. CURRY ENGINE ROOM TELEGRAPH Original Filed March 14, 1946 3 Sheets-Sheet 5 HERMAN H.CURRY INVENTOR Patented Feb. 2, 1954 U NITED STATES OFFICE ROOM TELEGRAPH Herman H. Curry, Imterne'ss; Fla.

Original; application March .14, 1946, Serial no.

654,489, new Patent No. 2,579,476, dated December 25., 1951. Divided and this application Augusta 1951, Serial No. 243,569

6 Claims.

.1 The invention described herein may be manufactored and useduby-or tor the Government oi the United States for governmental purposes without the=pagyment tomeof any royalty thereon iii-accordance with the provisions-of the act of .April 30; 1-928 -(Chi460, 45 Stat; L. 467).

This invention relates to systems :for transmitting motion between two or more remote stations and particularly to an improved electrically controlled engine room telegraph.

This application is a division of my co-pendmg application Serial No.- 654,,48&; .fo-r Engine Room Telegraph, filed Mar-ch 14, 1946, now Patent llo. 2579;476, December 25., .1951.

Heretoi-ore, complicated and costly electrical and mechanical telemetric devices have been proposed for transmitting signals between remote station's, "such as the bridge :and the engine room one. vessel. This is especially truein those cases where more than one transmitting device was used 'on' the bridge for sending signals to the en- .gineroomreceiver. Usually, it is desired tohave signals sent to the engine room from at least three positions on the bridge of a; vessel; .ifor example, the'wheelhouse; and the starboard and port wings of thebr idge; In the past when such plurality of bridge transmitting units were: employed, either complicated mechanical linkage connected all the: transmitting units-to a single transmitting device self-synchronized with a ,receiving device in the engine room; or if the transmitting stations were: electrically interconnected, a complicated panel: of transfer relays was employed' for connecting the last "operated transmitten unit-to th'e' 'engine room receiver. The mechanical linkage installation was subi ect-to t'freezing, added frictiontothe system 'and- Was'difioult to install-and maintain in: satisfactory operating condition; The electrical installation utilizingtransfer relayswascostly-to install, was subject to electrical failure and obiectionable because the last transmitter to be operated showed the true indication while:the remaining transmitters were "unaffected therebyand the different control positionsindicated thereon led to confusion.

An important objector thisxinvent-ion' is to provide an-improved motion transmission system especially adapted for signaling; controlmovarnents between a pluralityof transmitting stationsand one or more receiving stations :such that all stations show the last'rsignal transmitted.

Another object of the-inventionisto provide -an electrical transmission system operatively incora self-synchronizing electrical system which is automatically locked in any on of the control positions an only released from this condition upon movement of one of the transmitters toward another control position. Another object of this invention is to provide in such aselfsynohronizi'rig system an improved sense of touch or 'Teel ior facilitating the control thereof. A further object of this invention is to provide novel Warning and recording devices for indicating delays or errors transmission and reception of signals. V

More specifically, this 'm'ventionas applied to engine room telegraph provides .a novel controlling mechanism which releasably holds all the transmitting and receiving devices any control position selected and which is operable to release the system for operation when any one transmitting device is moved toward another control position. This is accomplished in the illustrated embodiment of the invention herein by the provision of one or more novel holding devices in the .form of a toothed or star wheel having a roller detent yieldingly pressed into engagement therewith and an electrical device responsive-to current flow in the self-synchronizing circuit for retracting. the detent from engagement with the star wheel. .A novel feature of the invention is the corresponding relation of the star wheel holding means to the-various control positions of the system such that when all the operating parts of the-system have followed up the transmitting device, the reengagement of the roller detent with the star wheel automatically centers all the transmitting and receiving de-.

vices to the mid-point of the control position selected. The requirement that a transmitting device be first moved toward another position-beforethe detent holding means releases the system provides a resistance in the system which the operator must overcome. This requires little manual effort but the resistance enooun-teredimproves the feel of the system to the operators control. Furthermore, upon synchronization of all the transmitting and receiving devices, the operator can feel the system'seeking the center of thenearest scale position.

The engine room telegraph ofthis invention incorporates a repeat-back self-synchronizing system whereby the-engineroom answers the signal from the bridge-and indicates to the bridge the-control-movemen-t exercisedover the engine. Preferably the-- repeat-back system is similar to the transmission system from the bridge and includesall the stations on the bridge. Each station, whether on the bridge or in the engine room, has a motion transmitting device and a motion receiving device preferably arranged side by side in one unit. Each station unit has a pointer and scale for indicating the control positions of the bridge control system and a pointer and scale for indicating the control positions of the repeatback system. The motion transmitting device of each station unit is provided with a control handle for moving the system in which it is associated. Since both systems are self-synchronizing, the movement of any control handle, whether in the control system from the bridge units to the engine room or in the repeat-back system from the engine room unit to the bridge units, is followed by movement of all transmitting and receiving devices in the system. The novel detent holding means elastically restrains both systems in their respective control positions except when an operator intentionally makes a change in the control position.

In order to warn personnel of any delay or error in acknowledging the transmission and receipt of signals, novel alarm devices are provided. An important object of this invention is I to provide warning devices electrically associated with the bridge and repeat-back systems which sound an alarm or otherwise indicate a, failure of either system to synchronize after a short delay, and which further sounds an alarm or otherwise indicates a warning when the acknowledgement or answer of the repeat-back system does not agree with the bridge control system.

A further object of the invention is to provide a novel recording device for graphically indicating the control movements transmitted from the bridge and acknowledged by the engine room. It is intended that this recording device be in op-= eration at all times. Of special significance is the provision of special means for varying the speed of the graphic recorder. In normal operation, the speed is relatively slow, but a novel provision automatically increases the speed of the recorder when errors in transmission and acknowledgment occur resulting in a graphic amplification which serves as a clearly understandable record of the event. A further novel feature is the provision of a manual control for increasing the speed of the recorder for use at times when it is expected that many signals will be transmitted to the engine, such as when docking or undocking a vessel.

In the drawings,

Fig. 1 is a diagrammatic view of a preferred form of the invention in which the several parts thereof are shown in a position registering t p n Fig. 2 is a diagrammatic-view of a modified form of the invention wherein recording means are applied to the engine room telegraph system, such means shown registering an error on the part of the engine room operator in operating the repeat-back signal device.

Fig. 3 shows a modification.

Referring more particularly to Fig. l, the system comprises a plurality of transmitting stations which may be located on the bridge or deck of a ship, the operation of any one of which will produce a corresponding operation of the receiving station which may be located in a remote place, such as a ships engine room. The deck indicator or transmitter H is adapted to be mounted on the port wing of the bridge, the deck transmitter l2 in the wheelhouse and the deck transmitter I3 on the starboard wing. The en- 4 gine room receiver I4 is operated by these deck transmitters.

The transmitters H, i 2 and it are identical and each thereof comprises a shaft l5, suitably journaled for rotation, upon which are affixed the three phase rotor windings it of a self-synchronous machine or motor H. A pointer I8 is carried at one end of the shaft and operates around the face of the dial 19 which bears suitable indicia thereon. A controller or handwheel 2B is affixed to the end of the shaft to permit rotation thereof to any desired position. To releasably and yieldingly retain the shaft in adjusted position, a star wheel 2i is aihxed to the shaft. This star wheel has seven notches which correspond to the seven positions usually used in a ships engine room telegraph and correspond to the signal stop and three speeds ahead and three astern. The wheel is essentially an eight pointed star and the portion thereof which is unused is bridged as at 22 so that the detent, subsequently described, will automatically force the wheel into the positions adjacent this particular bridged section should the shaft be rotated too far. A roller detent 23 is mounted adjacent this star wheel and rides over the edge thereof. This detent is carried by an arm 24 connected to the core of a solenoid 25 which when energized serves to withdraw the detent from engagement with the star wheel. A lever 26 has one end engaging the axle of the star wheel and the other end thereof resting on a fixed pivot 21. A spring 28 attached to the lever serves to hold the detent into engagement with the star wheel. It will be seen that the detent will force the star wheel into a definite angular position and will serve to positively position the pointer 18 on the dial. This is particularly important as the synchronizing torque in systems of the kind here used decreases with the decrease in the angle of displacement so that at small angles the torque is insufiicient to produce exact synchronism of the transmitter and receiver. This may lead to a variation in the reeciver pointer which would cause confusion in the engine room. With the star wheel, however, the detent serves positively to position the transmitter and receiver in the same angular position once movement of the wheel permits the detent to appear over the appropriate notch. The shaft may be turned by hand against the restraining influence of the detent, but the electrical machine aiiixed to the shaft may not necessarily provide enough torque to rotate the shaft against the detent. The end of the shaft l5 opposite to that carrying the hand wheel 20 carries an annular commutator 29 lying in a plane normal to the shaft and supported concentrically about the axis of the shaft by a radial member 30. The commutator 29 has a section thereof removed for a purpose subsequently described. Operatively associated with the rotor winding N3 of the machine I! is a single phasestator winding 3|.

Deck transmitters I! and I3 are identical in structure with deck transmitter l2 and no further description thereof is deemed necessary. Like parts bear similar reference numerals.

The engine room receiver I4 is similar to the transmitters described above and comprises a shaft 32 journaled for rotation, to which is affixed a rotor winding 33 of a self-synchronous machine 34, a star wheel 35 of the same configuration as star wheel 2|, and a commutator 36 positioned in the same manner as commutator 29. A pointer 31 is provided, but no hand wheel, for operation so that the shafts of the deck receivers and engine room transmitter may rotate without the restraining effect of the detents operating on the star wheels.

Each of the deck stations has an electric bell H2 connected in series to a time delay device H3 of conventional type. This device may be set for any selected period of time, six seconds for example. The bell and time delay device are connected to the line through the brush 35 and commutator 29 by suitable lead wires. These wires have been shown connected directly to the brush and commutator to simplify the drawing, but any suitable connection such as slip rings and contacts may be used. It will be seen that when the shafts I! and I are angularly positioned so that the brush 85 is opposite the gap in the commutator the alarm will not be energized. But if the shafts are angularly displaced the brush 85 will contact the commutator to complete the alarm circuit and cause the bell to ring after a predetermined time interval.

The engine room receiver and repeat-back transmitter are similarly provided with an elec tric bell H4 and a time delay device H5 connected thereto. These two devices are connected to the line across the brush I6 and commutator 36 so that as long as the shafts 65 and 32 are angularly disposed in a position to place the brush I6 in the gap in the commutator 33, the alarm will not be sounded. However, any angular displacement of one shaft with respect to the other will energize the alarm circuit.

The operation of the device is as follows: In its initial setting, assumed to correspond to stop on the dial, all of the equipment is disposed as indicated in Fig. 1. That is to say, all indi cators point to stop on the dials, the roller detents all bear on the star wheel to hold the pointers in position and the brushes are positioned adjacent the gap in the commutators. When it is desired to transmit a signal to the engine room, any deck transmitter may be operated. For example, assume that the wheelhouse wing control is used to transmit the ahead signal to the engine room. The controller or hand wheel is turned to rotate the shaft I5 in a counterclockwise direction against the restraining effect of the detent 23 operating on star wheel 2|. The operator thus has a very definite feel that the system is properly locked in position. This turning also causes commutator 29 to contact the brush 85, completing the alarm circuit, and also displaces the rotor I3 of the selfsynchronous motor H with respect to the rotor 33 of the receiver I4. This angular displacement causes a current to flow in the conductors I93 connecting the rotor windings which energizes relay I05 to close switch I94, thus energizing the solenoids and 44 of the wheelhouse control to withdraw the detents 23 and 40 from their respective starwheels, making the shafts free to rotate. If the engine room receiver fails to rotate to a position corresponding to that of the wheelhouse transmitter, the alarm I I2 will sound after a six second delay. If the shaft 32 assumes the same angular position in which shaft I5 of the wheelhouse transmitter was placed, the pointer 31 will turn to ahead on the dial 38. It should be noted that movement of the shaft 32 has placed commutator 36 in contact with brush I6 to complete the circuit for the alarm H4. If the engineer does not respond within one second, this alarm will sound. The engineer, observing this message, then grasps controller 68 of the engine room transmitter 64 and turns the pointer 66 to ahead. The rotation of shaft 65 will cause the brush it to disengage the commutator 36, assuming a position adjacent the gap therein, thus breaking the alarm circuit. This angular movement of the transmitter '64 is made against the restraining influence of the detent I2 engaging the star wheel 1 I. It also produces an angular displacement with respect to the deck receiver 81 and the current in the conductors connecting the rotors 89 and I0 actuates the relay III to close switch III] to energize the solenoids 83 and I5, withdrawing the detents 8| and I2 from their respective star wheels, thus permitting the motor 90 to rotate shaft I! to move the brush 85 to the gap in the commutator 29 to deenergize the wheelhouse alarm circuit. If the engineer does not perform the repeat-back operation within six seconds, the deck alarm H2 will sound.

When the relay III is energized to permit unlocking of the shafts I! of receiver 8'! and shaft 65, the relay 96 is also energized to close the solenoid circuit of deck receivers 86 and 88 thus unlocking their respective shafts to permit the pointers 78 to register the same reading as that of receiver 8?.

The operation of the system from either of the wing control stations is identical with that set forth above in connection with the wheelhouse control.

Referring more particularly to Figure 2, I have shown a recording system combined with the transmitting system of the general type shown in Fig. l, but somewhat simplified for a readier comprehension thereof.

Deck transmitters H3, H9 and I20 comprise self-synchronous electrical machines, each having primary windings I2I connected to a source of alternating current by conductors I22. The three phase rotor windings I23 are connected in parallel. Deck transmitter I 2I has a shaft I24 to which is affixed a pointer I25 which operates over dial I26 bearing suitable indicia. The several ahead and astern speeds, corresponding to slow, one-half and full speed, have not been indicated in the interest of clarity. The pointer, however, is turned to indicate half speed ahead. The shafts, dials and pointers have not been illustrated for the other transmitters.

The engine room receiver I2'i comprises a self synchronous alternating current machine having a single phase stator Winding I28 and a three phase rotor winding I29 afiixed to the shaft I39. A pointer I3I is carried by one end of the shaft and operates over dial I32 upon which suitable mdicia (not shown) is inscribed. The rotor windings i 29 of the receiver are connected to the rotor windings I23 by conductors I33 to permit synchronous operation of the transmitters and receiver in a manner well known in the art.

The shaft I39 has a star wheel I34 affixed thereto which is engaged by a roller detent I35 held into engagement therewith by a spring biased lever I38. The star wheel is fundamentally an eight point star having two points bridged as at I35 to provide seven recesses which correspond to the seven speeds, viz., stop, three speeds astern and three ahead. When the detent I35 rests between the teeth the wheel is positively positioned and holds the pointer I3I in a definite position on the dial I32. A solenoid I 31 is operatively connected to the detent for removing the detent from engagement with the star wheel. The solenoid is connected to the source of power by conductors I39, one of which contains a switch I40 in series. therewith. A relay I4I comprising oops I 42 in the conductors; I33 and cores I43 Serves to operate switch I40 to complete the circhit to seismic; I31 to unlock the shaft I30 of the receiver for rotation to permit it to assume an angular position correspondingto that of the transmitter whereupon switch I40 opens and the detent again engages the star wheel. An alarm I44 is inserted the solenoid circuit for soundingin the engine room when a signal is transmit- The other end 6f the's'ha'ft I30 carries a commutator I45 supported thereon by a radial arm I46. The commutator is annular in form and mounted in a plane concentric with and normal to the axis of the shaft; The shaft also carries a bevel gear I41 meshing with a second bevel gear I48 attachedtoone end of shaft I40 rotatably journaled in bracket I50.

The repeat-back system comprises an engine room transmitter II hav-ing'a single phase stator winding; I52 and a three phase rotor winding I53 affixed to shaft I54 journal'ed for rotation and axially aligned with and spaced from shaft I30. one end of the shaft carries a controller or hand wueei I55 and a pointer I56 operating over a rises dial I51 carrying suitable indicia. The Qther'end of the shaft carries a brush I58 axially displaced from the shaft and wiping the commutater I45, except when the brush. is opposite the gap therein, to complete a control circuit described below; The shaft I54 also has abevel gear I 53 affixed thereto which engages a bevel gear I60 afiixed. to the end of a shaft I61 rotatablyjournaled in bracket I62; The, rotor winding I53 is connected to the parallel connected three phase rotor windings. I18, of deck receivers I19, I80 and ISI. by conductors,v I63. The single phase primary windings I82 are connected to a source of single phase, power. These receivers may be supplied with pointers and dialsas shown in Fig. 1.

The shafts I46 and I6! have, radial arms I63 and IE4; respectively; the, ends of which carry styli I65 and I66. The recording, device upon which the stylus operates comprises a pair of drums t I51 and I68 mounted ona shaft I=69- driven by an electric motor I through a worm and wheel drive; I,1I.- The, motor is connected to the line by conductors I12: A resistance I13 in this line may be out into or out of the motor circuit to change; the speed thereof by switch I14 which may be moved to contact one end of the resistance or one endof a conductor I15. paralleling saidresistance. The switch I14 is operated by a solenoid I16. Thissolenoid' circuit includes the brush I58 and commutator I45, conductors I11 connecting-the said. elements; to the line inseries with the solenoid I16. When. the brush I50 engages. the commutator I 45, the solenoid I16 is energized to operate the, switch I'II4 to boy-pass the resistance I 13 and thereby increase the speed of the motor I10 to rotate the drums I68.and I69 at a greaterspeed, The switch I14 may also be manually operated. by means of a knob I95 attached thereto,

Paper tap s, I84and I85 pass: over drums I68 and I66, respectively, and receive the marks made by the stylus. The paper may be oalibrated as. shown; having a: centrally disposed line I66 indicating stop and lines I 61, Iflfiand I89 corresponding to slow, one-half and full speed ahead, respectively, and lines I60; I-B'I- and; I92 indicating slow, one-half and full: speedastemv Arms I53; and I64 move the styli I65 and. I66

over these tapes in a direction and to a degree corresponding to the movement of the receiver shaft I30 and transmitter shaft I54 by reason of the beveled gears coupling the shafts to their respective stylus arms. The trace I93 on tape I84 is made by stylus I65 and the trace I84 'on tape I05 by stylus I66.

While a variable speed motor has been shown, it is obvious that any suitable speed varying means may be used in lieu thereof, such as a variable speed transmission in which case, the solenoid I16 would operate the gear shifting means.

The operation of the device is as follows: With the deck transmitter set for 'stop the shaft I30 oi the receiver I21 will be in a corresponding position; If the transmitter I5I' is also set for stop, the brush I56 will be adjacent the gap in the commutator I45, thus opening the circuit to solenoid I16. This will keep the switch in a position to out in the resistance I13 and the motor will operate at slow speed to avoid excessive use of tape. The bevel gears will turn their respective stylus to the lines I86 on the tapes indicating that both receiver I21 and transmitter I 5I, are in agreement.

However, if the deck transmitter I I8 is turned to half speed ahead as. shown in Fig; 2, the current flowing in conductors I33 will operate relay I4! to close switch I40, energizing solenoid I31 to remove detent I35 from the star wheel whereupon the receiver assumes the same position; as the deck transmitter as shown by pointer; I3I of the receiver. Relay I4I will then openswitch I40 to permit thev detent to hold the shaft I30 iILDOSi" tion; Turning ofthe shaft I30 also rotatescommutator I45 counterclockwise intoengagement with the brush I58, thus completing the circuit to the motor control solenoid I16 to speed up the motor I10 by cutting out resistance I13, l -'totation of the shaft I30 also rotated, shaft I49 through bevel gears I41 and I48 a corresponding amount so that the stylus I65 moved from the line I86ontape I84 to line I88registeringa deck signal of one-half speed ahead. 4, V

For purposes ofillustration Fig: 2 has. been drawn to illustrate the applicationof an: erroneous repeat-back signal. The operator has turned the transmitter pointer I56 tov half speed astern. This movement of shaft I54 does. not disengage the brush I58 from the commutator I45 ,"the motor I10 continuing to run at high speed. Rotation of the shaft I54 has also rotated shaft I6I through bevel gears I56 and I60 to turn. the arm I64 to position the stylus I66 on the tape I35 to register thereon one-half speedaster'na as shown by the trace I94. A record has thus been made showing the signal received as well as the one repeated back.

The operator may turn the pointer 156 of transmitter I,5I through to one-half speed ahead, whereupon brush; I58 will be opposite the gap in the commutator, thus breaking the circuit to the motor control solenoid I16 and slowing down the, motor I10, This, movement ofshaft I5 will. also cause stylus I66 to be moved to register a corresponding impression on the tape I85.

Having provided means for recording the signals between: the bridge and; engine room, it is desirable also to indicate on the tape other factors relating thereto; such as time, propeller speed, propellerrevolutions, position of the prime mover throttle or control lever, etc: In Fig. 2, I have shown a printing clock- I196 for recording 11 the time on the tape I85 when the engine room receiver and transmitter are not in agreement. The printing clock is of a type well known in the art and no further description thereof is deemed necessary other than to state that it has a printing arm carrying hour and minute hands and the date whose imprint is made on the tape at predetermined intervals when its operating solenoid (not shown) is connected to a suitable source of power. The printing arm of the clock I96 overhangs the edge of the tape I85 adjacent the end of drum I61. The means for forcing the printing arm into engagement with the tape is connected in series with the brush I53, commutator I45 and the solenoid I16 so that printing of the time is only effected when the engine room receiver I21 is angularly displaced with respect to the engine room transmitter II. The marks made by the printing clock have been shown at I91 in Fig. 2. From this record, the time the signals were recorded on the tapes may be found. While only one printing clock has been shown, it is of course obvious that another similar clock could be used in connection with tape I80 for the same purpose. It is also obvious that the clock could be made to print the time whenever a certain amount of tape had passed over the drum. This could be effected by having projections on the tape at fixed distances which would operate a switch to energize the clock to record the time.

It is also obvious that other recording instruments could be substituted for, or used with the printing clock shown in Fig. 2 and the same energizing circuit could be used for operating such instruments in the same manner in which the clock is energized.

In Figs. 1 and 2, the solenoids which retract the detents from the star wheels are connected to the line by switches operated by relays controlled by current flowing in the conductors connecting the secondary windings. In Fig. 3, I have illustrated a system which uses a switch operated by movement of the transmitter detent for controlling the solenoid circuit.

The transmitter I98 comprises a shaft I99 upon which is affixed a three phase rotor winding 200, a star wheel I similar to those previously described, an indicator 202 and a controller in the form of a hand wheel 203. The bridged portion between one pair of teeth shown on the star wheels in Figs. 1 and 2 has been omitted in star wheel 20I to permit the ready disclosure of the roller 2I0. It is, of course, obvious that this roller could be mounted next to the roller detent 205, in which case the star wheels previously described could be used. A single phase primary winding 204 is associated with the rotor winding. A roller detent 205 is mounted on the end of a rod 206 carried by the core of a solenoid 201. The detent is yieldingly held into engagement with the teeth of the star wheel by a pivoted lever 208 one end of which engages the axle of the detent. A spring 209 holds the detent against the star wheel, positively positioning the transmitter in a predetermined position. A second roller 2 It is mounted to ride upon the teeth of the star wheel 20I and is yieldingly held into engagement therewith by a pivoted lever 2H and a spring 2 I2. A rod 2I3 afilxed to the roller 2I0 has its free end attached to the movable member of switch 2I4, in the line 2I5.

The receiver 2I6 comprises a shaft 2I1 carrying an indicator 2I8, a rotor winding 2I9 and a star wheel 220. A roller detent 22I is. yieldingly held into engagement with the star wheel by a pivoted lever 222 biased by a spring 223. The detent is fastened to the core of a solenoid 224 for retraction from engagement with the star wheel when the solenoid is energized. Stator winding 225 is operatively associated with the rotor winding 2 I9. Other features of the transmitter and receiver have not been illustrated in the interest of simplification.

The transmitter and receiver stator windings are connected to a source of single phase alternating current by conductors 226 and the rotor windings of the two machines are connected by conductors 221. The conductor 2I5 puts the switch in series with the parallel connected solenoids 201 and 224 across the line.

The operation of the system is as follows: Rotation of transmitter shaft I99 by means of hand wheel 203 will force the roller detent 205 from between the teeth of the star wheel 20I against the tension of spring 209. At the same time, roller 2I0 is similarly forced to ride upon the adjacent tooth moving the rod 2I3 in a vertical direction against the tension of spring 2I2 to close switch 2I4. This serves to energize solenoids 201 and 224 to retract roller detents 205 and 22I from the star wheels 20I and 220 leaving the receiver shaft free to align itself angularly with the transmitter shaft under the influence of the synchronizing torque generated by current flowing in conductors 221. The switch 2 I4 is designed to close before the roller 2 I0 rides over the point of the tooth, preferably when the shaft I99 has been rotated about 10 in either direction. When the roller 2I0 rides over the point of the adjacent tooth, it will assume a position between that and the next tooth and will open the switch 2I4 to deenergize the solenoids 201 and 224 whereupon the springs 290 and 223 will force the detents 205 and 22I into engagement with their respective star wheels to yieldingly hold said shafts against rotation.

While but one receiver and one transmitter have been shown in Fig. 3, it is to be understood that the control system for the solenoids could be substituted for that shown in Figs. 1 and 2. Where there is a plurality of transmitters, it would only be necessary to connect the switches for each transmitter, corresponding to switch 2 I4 in Fig. 3, in parallel and these in series with the parallel connected solenoids as shown in Fig. 3 so that the closing of any switch by movement of a transmitter shaft would close the circuit for all the solenoids to permit all of the devices to synchronize simultaneously.

While I have described the preferred form of my invention, I do not wish to limit myself to the precise details as shown, but wish to avail myself of such variations and modifications as may come within the scope of the appended claims.

I claim:

1. An engine room telegraph system comprising, in combination, a deck indicator unit and an engine room indicator unit each having a motion transmitting self-synchronous motor and a motion receiving self-synchronous motor and means for indicating the respective positions of the motors, electric circuit means connecting the motion transmitting motor of each unit with the motion receiving motor of the other unit for self-synchronous operation, an alarm device, an electric circuit for operating said alarm, two coacting members each having a fixed positional relation with a different one of said motors in one of said units, said coacting members being connected in said alarm circuit and arranged to close said alarm circuit and operate said alarm when the motors in said last mentioned unit are not in positional agreement, and means for interposing a time delay in said alarm circuit preventing operation of said alarm device until after a predetermined interval of time, a graphic recorder having variable speed means for continuously advancing its recording strip, means connected with said motion transmitting motors for recording on said strip the direction of movement of said motion transmitting motors in each of said units, and means responsive to misalignment of the motors in one of said units for increasing the speed of advance of said strip when the motion transmitting motors are not in positional agreement.

2. A system for the transmission and reception of angular motion between two remote stations, comprising a motion transmitting device and a motion receiving device at each station, connections between the motion transmitting device at each station and the motion receiving device at the other station to reproduce in the receiving device at one station any movement applied to the transmitting device at the other station, recording means connected to the transmitting and receiving devices at one of said stations for indicating the successive positions of said last mentioned devices on a continuously advancing strip, and means responsive to misalignment of said devices connected to the recorder for automatically varying the speed of advance of said strip when the transmitting devices at each station are not in positional agreement.

3. A system for the transmission and reception of angular motion between two remote stations, comprising a motion transmitting device and a motion receiving device at each station, connections between the motion transmitting device at one station and the receiving device at the other station to reproduce at the receiver of one station any movement applied to the transmitting device at the other station, a graphic recorder having a continuously advancing strip, means connected to the transmitting and receiving devices at one station for indicating on said strip the successive positions of the transmitting and receiving devices at said last mentioned station, and means responsive to misalignment of the devices at said last mentioned station for automatically increasing the speed of advance of said strip when the transmitting devices at each station are not in positional agreement.

4. A system for the transmission and reception of angular motion between two remote stations, comprising a motion transmitting device and a motion receiving device at each station, connections between the transmitting device at each of said stations and the receiving device at the other of said stations to reproduce at the receiving device of either of said stations any movement applied to the transmitting device at the other station, a graphic recorder having a continuously advancing strip, means for varying the speed of said strip connected to the transmitting and receiving device at one of said stations for indicating on said strip the successive positions of the transmitting and receiving devices at said last mentioned station, and means responsive to the misalignment of the transmitting and receiving devices at said last mentioned station for automatically increasing the speed of advance of said strip when the transmitting devices at each station are not in positional agreement, and manual control means connected to said speed varying means for varying the speed of advance of said strip independently of said automatic means.

5. A system for the transmission and reception of angular motion as claimed in claim 2 with a second recording means for printing data upon said strip, said means responsive to misalignment being connected to and operating said second recording means when said devices at each station are not in positional agreement,

6. A system for the transmission and reception of angular motion as claimed in claim 2 and a printing clock positioned to print the time on said strip, said means responsive to the misalignment being connected to and operating said printing clock when said transmitting devices at each station are not in positional a reement.

HERMAN H. CURRY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name v Date 579,473 Davidson et al Mar. 23, 1897 974,562 Foote Nov. 1, 1910 991,585 Wilson et a1. May 9, 1911 1,054,206 Isakson et al 1. Feb. 25, 1913 1,138,226 Kenney May 4, 1915 1,317,672 Ahern Oct. 7, 1919 1,345,626 ONeil July 6, 1920 1,597,828 Roucka Aug. 31, 1926 2,565,271 Sealander et al. Aug. 21, 1951 2,579,476 Curry Dec. 25, 1951 

